Tubulous boiler walls



Feb. 26, 1963 R. H. EVANS TUBULOUS BOILER WALLS 3 Sheets-Sheet 1 Filed March 17, 1959 liilll In ventor Riqhard H. Evans Attorney Feb. 26, 1963 R. H. EVANS 3,

TUBULOUS BOILER WALLS Filed March 17. 1959 s Sheets-Sheet 2 Inventor Richard H. Evans W Attorney Feb. 26, 1963 R. H. EVANS TUBULOUS BOILER WALLS 3 Sheets-Sheet I5 Filed March 17. 1959 lnvenlor Richard H. Evans Attorney 3,078,830 TUBULOUS BGHLER WALLS Richard H. Evans, London, England, assignor to Bahcoch & Wilcox Limited, London, England, a British company Filed Mar. 17, 1%9, Ser. No. 799,869 Claims priority, application Great Britain Mar. 17, 1958 23 Claims. (Ci. 122-6) This invention relates to tubulous boilers of the kind having a chamber providing a combustion or/and radiation space with upright walls and at the inner side of the walls a screen of wall tubes and more particularly to high pressure boilers of large capacity adapted to generate steam at high temperatures of superheat. Commonly, a boiler designed to give a large output of steam at high pressure and high temperature utilizes a chamber of great height for aflording a combustion or/ and radiation space and one mode of supporting the chamber walls is to hang them on upright suspended wall tubes which are able to expand downwardly. While in the past this method has frequently proved advantageous, it becomes less attractive as increased steam pressure or increased wall height and weight necessitates undue thickening of the tube walls. Moreover, the method tends to make diificult tube replacement or repair. When a horizontal tube arrangement is desired, the tubes cannot be used to support the walls. In such case, a construction may be adopted in which cantilevers projecting from upright steelwork serve to support wall sections and the wall tubes. The steelwork, however, must be located adjacent the chamber walls and tends to obstruct access to the Walls and to present undesirable obstructions in the neighbouring space below the chamber.

An object of the invention is the provision of an improved wall construction enabling good access to be obtained to the outside of a wall without using wall tubes for its support.

The present invention provides, in a tubulous boiler having a chamber providing a combustion or/ and radiation space with upright walls, an upright wall having at its inner side a screen of wall tubes and mounted in superjacent sections on vertically spaced buckstays suspended by tension members, the buckstays and tension members being located outside the chamber.

By way of example, an embodiment of the invention will now be described with reference to the accompanying drawings in which:

FIGURE 1 is a vertical section through part of an upright wall of a boiler and illustrates the means on which the wall is mounted. The upper part of FIGURE 1 is a section on the line I-I of FIGURE 3 with certain details cut away or omitted, while the lower part of FIG- URE 1 is cut away to the line Iala of FIGURE 3;

FIGURE 2 is a section on the line Il-II of FIGURE 1 of the means on which the wall is mounted;

FIGURE 3 is a section on the line IIIIl-I of FIGURE 1 of the means on which the wall is mounted and showing the wall tubes mounted on said means; and

FIGURE 4 is a section of the corner of the furnace on the line IV-IV of FIGURE 1.

The wall of which a section is shown in FIGURE 1 is one of the walls of the rectangular radiation chamber of a forced-flow boiler of conventional overall design, in which fluid is circulated through horizontal tubes by means of a pump.

The walls are mounted on rectangular loops formed from buckstays and the buckstays are suspended by tension members. The firebrick facing, sealing layer and insulating sheath of each wall are formed in sections and each section is bottom supported from one of the buckstays. In the particular embodiment described, the walls 3,078,839 Patented Feb. 26, 1963 are feet high, the vertical spacing between the buckstays is about eight feet and the horizontal spacing between the tension members associated with any wall is about six feet.

The buckstays are of I-section with their web portions 2 horizontal and their inner flanges 3 and their outer flanges 4 vertical. The upper of the two buckstays 1 shown in FIGURE 1 is suspended by rods 5 in tension and the lower is suspended by the rods 6 in tension connected at their upper ends to the lower ends of the rods 5. Further rods 7 in tension are connected at their upper ends to the lower ends of the rods 6 and support the next lower buckstay (not shown).

The vertically aligned groups of rods 5, 6, and 7, each form a tension member and several vertically spaced buckstays are all supported from the same tension members. The rods 5, 6, and 7 are of circular section and are threaded at each end. The lower end of the rod 5 passes through a hole in the web 2 of the upper buckstay 1, near the inner flange 3, and the web rests on a washer 8 held in position by a nut 9. When the nut 9 is in its final position, it is spot welded at 1G to the rod 5.

The other buckstays 1 associated with the wall are similalry suspended by means of nuts 9 and washers it from the lower ends of rods and each rod is connected at the upper end to the lower end of the rod immediately above it by means of a turn-buckle 11 into which these ends are screwed. The thread at the lower end of each rod is of opposite hand to the thread at the upper end of the next adjacent rod below it so that by rotating the turnbuckle 11, the distance between adjacent buckstays 1 can be varied without turning either of the associated rods. When the desired separation has been achieved, the turnbuckle 11 is welded to the associated rods at 12 and 13.

To prevent the buckstays 1 from bending under the upward pressure exerted on the webs 2 by the tension members and the downward pressure exerted on the flanges 3 and 4 by the loads connected to them, channel section braces 14 are welded across the webs 2, the bottoms of the braces 14 being welded to the upper surfaces of the webs 2 and the ends of the braces 14 being welded to the facing surfaces of the flanges 3 and 4. The tension members extend between the side walls of the braces 14 and pass through holes in the bottoms of the braces 14.

As a result of the way in which the wall is supported, the load carried by any rod depends on its distance from the top of the wall, the load decreasing progressively downwardly. The diameter of any rod below the topmost may therefore economically be less than that of the rod or rods above it and such a difference of diameter is shown in the rods 6 and 7.

The upper end of the uppermost rod is connected to a supporting framework in any suitable way of which several are known from the conventional practice of top hung walls. For instance the upper end of the rod may be provided with a clevis and this may be connected by means of a pin passing through an eye at the lower end of a further rod and lying in the clevis. The upper end of this further rod is provided with a head that rests in a bearing surface of the supporting framework.

The firebrick facing 15, the sealing layer 16 and the insulating sheath 17 of the wall are supported in sections from below by the buckstays 1 by means of brackets 13 booked in pairs on the inner flanges 3 of the buckstays 1. The brackets 18 of each pair are situated one on each side of a tension member (see FIGURE 2) andeach bracket 18 consists of the plate 19, having a downwardly extending flange 20 at one edge and an upwardly extending ridge 21 near the opposite edge, and a plate 22 extending downwardly from the plate 19 and provided with a rearwardly extending flange 23 at its lower edge. A triangular reinforcing web 24 extends between the plates 19 and 22.. When the flange 20 is hooked behind the upper edge of the flange 3 on the buckstay 1, the flange 23 rests against the lower edge of the flange 3 to hold the plate 19 horizontal.

Plates 25, acting as shelves, are supported by the brackets 13, each resting at its left hand end on the right hand bracket 18 of a pair and at its right hand end on the left hand bracket 18 of the next adjacent pair. A slot 26 is formed in each end of each shelf 25 and the ridges 21 engage with these slots 26 to locate the shelf 25. The shelf 25 is reinforced by the rib 27 extending lengthwise of its lower face.

The firebrick facing 15 of each section is built up on the lowest course of bricks 3t resting on aligned shelf plates 25. The bricks 30 of this lower course are wider than the average width of the facing 15 and project outwardly beyond the outer surface of the facing 15. Certain of the bricks 30 of the lowest course rest with one end on one end of one of the shelves 25- and the other end on the neighbouring end of the next adjacent shelf and so bridge the gap between the ends of the shelves. The front edge of each brick 3%) is provided with a downwardly extending tongue 31 overhanging the front edge of the shelf 25.

The courses of the facing 15 are built up on the lowest course in the usual way with their front faces aligned with the front faces of the bricks 30 of the lower course. There is an expansion gap 34 between the top of the uppermost course of each section and the brackets 18 that support the shelf above it and the bricks 32 of the uppermost course are each provided with a recess 33 at their upper front corners. The lower edge of the tongue 31 lies in this recess so that the gap between the top of one section and the bottom of the section above it is always closed. In addition to closing the gap, it will be seen that the tongue 31 also protects the shelves 25 from the heat in the chamber.

The horizontal tubes 35 that line the wall are supported on vertical beams 35 of T-shaped horizontal crosssection and the beams 3-5 are supported from the buckstays 1 by brackets 37.

Each bracket 37 consists of parts 38 and 39 at right angles to each other and reinforced by the horizontal web 40. The brackets 37 are mounted in pairs, with the parts 39 facing each other, by bolts 41 passing through the parts 32; and the inner flange 3 of the buckstay 1 and lying one above and one below the web 40.

Each beam 36 extends between a pair of brackets 37 associated with one buckstay 1 and a pair of brackets 37 associated with the next lower buckstay 1, the stern portion 4-2 lying between the brackets 37 of each pair. The upper end of each beam 36 is rigidly bolted in position, as at 43, while the lower end is allowed to move vertically relatively to the brackets 37 to accommodate differential thermal expansion. Thus at the lower end, the stem portion 42 is provided with a hole 44, elongated in the lengthwise direction of the beam 36, and a bolt 45, held in position by a cotter pin 46 is passed through the hole 44 and the parts 39 of the pair of brackets 37.

The stem 42 of the beam 35 lies between adjacent firebricks of the facing 15 while the cross piece 47 lies in a recess in the front faces of the bricks between which the stem 42 lies.

The tubes 35 are contiguous and are supported from the beams 36 by means of the hooks 48 which are welded to, and extend across the width of, the cross-pieces 47 which co-operate with hooks 49 welded to the tubes 35. The hooks 49 on any one of the tubes 35 co-operate with hooks 48 on every alternate beam 35, while hooks 49 on the contiguous tubes 35 above and below that tube 35 cooperate only with the hooks on the remaining beams 36.

It will be realized that since the tubes 35 are simply hooked in position, servicing and replacing them is extremely simple. Once in position, each tube is prevented from moving downwardly by the hooks and from moving upwardly by the next adjacent tube above it. To ensure that the uppermost tube cannot move upwardly, fingers 50 are fixed in position either when the bank of tubes 35 is complete or when the tubes 35 associated with each section of the wall are in position. The inner end of the finger St} is welded at its inner end to the top of a beam 36 and its outer end is curved to mate with an upper inner quadrant of the section of the uppermost tube 35.

The wall includes two metal casings (see FIG. 4)an inner casing lying between the firebrick facing 15 and the tension members 5, 6 and 7 and serving to position the insulating sheath 17 and an outer casing enveloping the buckstays 1 and the tension members 5, 6 and 7.

The inner casing is formed from plates 51a, which have outwardly extending flanges at their vertical edges, welded at'the outer edges of the flanges to the outer edges of the side walls of vertical ribs 51 of channel sections. The side walls of each rib 51 are cut away at each end to leave the ends of the bottom of the rib 51 projecting as an upper tongue 52 and a lower tongue 53. The length of the side walls of the ribs 51 after the ends have been cut away is just less than the separation between the lower edge of one buckstay 1 and the upper edge of the buckstay 1 immediately below it.

The tongues 52 and 53 each lie between the inner flange 3 of a buckstay 1 and the parts 38 of a pair of brackets 37. The lower tongue 53 is provided with a vertically elongated hole 54. The bolt 41 passes through the hole 54 and a spacing bush 55, of a width slightly greater than the thickness of the tongue 53, is clamped between the flange 3 and the part 33. As a consequence of the dimensions of the hole 54- and the bush 55, the rib 51 can expand downwardly thermally. The upper end of the rib 51 is clamped rigidly in position by the bolt 41, the packer 56 being included to compensate for the difference between the thickness of the spacer 55 and the tongue 52.

The inner casing is completed by rectangular plates 51a flanged at their vertical edges and having their horizontal edges tucked behind the plane surface of the inner flanges 3 of the buckstays 1. The horizontal edges are recessed at appropriate intervals to accommodate the parts of the hooks 18 that extend to, or overlap, the edges of the flanges 3. The outer edges of the flanges at the vertical edges of the plates forming part of the inner casing are welded to the outer edges of the side walls of the ribs 51. The rectangular plates referred to may be formed in one piece or be constituted by a plurality of smaller plates provided with outwardly extending flanges and connected together by being welded together along the outer edges of said flanges.

To prevent the buckstays 1 from tilting relative to the ribs 51, triangular braces 57 are provided in pairs with their vertical edges welded one to each of the side walls of the ribs 51 and their horizontal edges welded to the lower surfaces of the webs 2 of the buckstays 1. One of the pair of braces 57 that should properly appear in FIGURE 1 has been omitted so that details of the turn-buckle 11 could be shown.

An insulating sheath 17 is held outwardly of the tire- =brick facing 15 by an outer casing. The sheath 17 is clamped between the inner casing and the facing 15 intermediate its upper and lower edges by the bolts 58 passing through the ribs 51 of the casing. The heads of these bolts 58 are held in recesses in bricks, 59, projecting rearwardly from the rear face of the firebrick facing 15 and the casing is held between two nuts 60 and 61 on the bolt 58.

Sealing layer 16 is poured into position as a liquid after assembly of the firebrick facing 15 and the sheath 17 and allowed to solidify.

The outer casing is formed from rectangular panels 62 having flanges 63 at their edges and each spanning substantially the entire separation between adjacent buckstays 1 and having a width equal to the distance between adjacent tension members. The panels 62 are welded together at the outer edges of their vertical flanges 63a, the vertical flanges lying midway between a pair of adjacent tension members. They are held in position at their lower edges by means of spaced inverted V-shaped members 64 bolted at 65 t0 the horizontal flanges 63b and co-operating with upwardly projecting strips 66 welded at their lower edges to the upper faces of the webs 2 and lying lengthwise of the webs 2. The upper edges of the strips 66 project into slits 67 formed in the side Walls of the members 64-. The panels 62 are held in position at their upper edges by means of spaced V-shaped members 68 bolted at 69 to the upper horizontal flanges 63b and co-operating with the downwardly projecting stems of strips 76 of T-section. The stems of the strips 70 extend lengthwise of the web 2 and project into slits 71 formed in the side walls of the members 68. The stems of the strips 70 do not project as far as the bottoms of the slits 71 and it will be seen that the panels 62 are thus positioned but free to expand thermally.

The gaps between the bottom of each panel 62 and the top of the panel 62 immediately below it are bridged by members '72 of C-section. The edges of out-turned rims of the members 72 are welded to the outer edges of the horizontal flanges 63 and the members 72 are provided at their ends with vertical flanges 73 by which they can be welded together. By virtue of their shape, the members 72 can flex to absorb the effects of thermal expansion of the adjacent panels 62.

To prevent excessive transfer of heat to the outer casing while allowing it to be positively positioned relatively to the buckstays 1, thermally insulating packing is included at 90 between the V-shaped members 64 and 6S and the flanges 63 and at 91 between the edges of the outer flanges 4 and the members 72.

FIGURE 4 shows details of the construction of a corner of the furnace.

The buckstay 1 extending along one side projects beyond the edge of that side to the outer flange 4 of the buckstay 1 that extends along the adjacent side. A plate 80 is welded to the end of this buckstay 1 and bolted at 81 to the inner flange 3 of the buckstay 1 that extends along the first side.

The hooks 48 and 49 that lie nearest the corner are sufliciently far away from the corner to allow the parts of the tubes 35 lying between these hooks and the corner to bend to absorb the effects on the length of the tubes 35 of thermal expansion.

The bricks of the vertical ends of the facing 15 are tongued and the tongues engage with each other so that the corner of the furnace is closed.

The plate 51a at the corner of the inner casing extends between the extreme ribs 51 of the adjacent sides of the furnace and is bent to provide two limbs perpendicular to each other. A panel 62a of the outer casing, similarly bent at a right angle, is interposed between the extreme panels 62 at the adjacent sides of the furnace and is provided with vertical flanges 620 which are welded at their outer edges to the outer edges of the flanges 63a.

A cap piece 72a, having a contour in plan similar to that of the adjacent corner of the longer buckstay 1 (the plan being shown in FIGURE 4), is welded by means of flanges 73a at its ends to the flanges 73 at the ends of the straight members 72.

Although in the embodiment described, the tubes 35 are horizontal it will be seen that the structure described could be readily adapted for use with vertical tubes. In such a case, the tubes might be top hung and anchored to horizontal stays connected to, and extending transversely of, the beams 36.

I claim:

1. In a furnace chamber defined by upright walls, one of said walls comprising a plurality of separated, vertically stacked wall sections each including buckstay means for bottom supporting each of said vertically stacked wall sections to carry the load thereof, means for top supporting each of said buckstay means and load carried thereby from a superjacent wall section, and a group of horizontally disposed tubes screening each of said wall sections, each group of tubes being supported from the wall section stacked above the wall section screened thereby.

2. The invention defined in claim 1 wherein each wall section is provided with an inner facing of refractory material, and a lower wall section is arranged to form an expansion gap between the upper edge of the facing thereof and the lower edge of the facing of an upper wall section immediately above it, said refractory material projecting from one of said edges and cooperating with a recess formed in the other of said edges to provide a seal between the edges, and said projecting refractory material screening the means for supporting the upper wall section from below from the interior of the chamber.

3. The invention as claimed in claim 2, in which the means for supporting the upper wall section from below includes shelving resting on brackets supported by one of said buckstay means, and the projecting refractory material extends downwardly from the edge of the refractory material that faces the upper wall section across the front edge of the shelving and cooperates below the shelving with a recess in the upper edge of the facing of the lower Wall section.

4. The invention as defined in claim 1, wherein each wall section includes an inner facing of refractory material and an outer sheath of insulating material, upright ribs connected between adjacent buckstay means so as to accommodate for relative movement therebetween, and a metal casing at the outer face of the insulating material, said casing being connected to said upright ribs, and bolts extending through the insulating material for tieing said metal casing to said refractory facing.

5. The invention as claimed in claim 4 in which the buckstays are each provided with an upwardly extending and a downwardly extending flange adjacent the insulating material, said ribs being in the form of channels of which, at each end, the bottom projects beyond the sides in the form of a tongue, each tongue lies between the insulating material and a flange of a buckstay and is bolted to the flange, the connection between a tongue and a flange at one end, at least, of each rib being such as to allow longitudinal thermal expansion of the rib.

6. The invention as claimed in claim 5, in which the casing includes plates having outwardly projecting flanges at their side edges, the front edges of the flanges are welded to the ribs, and the top and bottom edges of the plates are located between the flanges on the buckstays and the insulating material.

7. The invention as claimed in claim 4, in which the metal casing is the inner of two metal casings, the other of said two metal casings being an outer metal casing spaced from the inner metal casing to envelop the tension members and the buckstays.

8. In a fluid heating unit having a chamber defined by upright walls, one of said upright walls comprising a plurality of vertically stacked Wall sections each including a firebrick wall portion, means for bottom supporting each of said vertically stacked firebrick wall portions, means for top supporting each of said bottom supporting means from the next superjacent wall section, fluid heating tubes screening each of said vertically stacked wall sections, and means for top supporting the screening tubes of the respective wall sections from the bottom supporting means of the next superjacent wall section.

9. In a fluid heating unit having a chamber defined by upright walls, one of said upright walls comprising a plurality of vertically spaced buckstays extending transversely of said wall, means supporting each of said buckstays in vertically spaced relationship, vertically disposed upright fire wall sections bottom supported by said buckstays, a

group of fluid heating tubes screening each of said fire wall sections, and means for top supporting the screening tube group of each section from the buckstay superjacent the wall section screened by the same tube group.

10. The invention as claimed in claim 9, in which the means by which the tubes are supported on the beams are such as to permit ready disengagement of the tubes from the beams.

11. The invention as defined in claim 9 wherein said means for top supporting said screening tube group of each section includes a vertically disposed column supported between an adjacent pair of said buckstays, means connecting said column between said pair of buckstays so as to provide relative movement therebetween to accommodate for contraction and expansion of said column, and means for supporting said tube group on said column.

12. The invention as defined in claim 9 wherein said means for top supporting the screening tube group of each section includes a vertically disposed beam supported between an adjacent pair of said buckstays, means connecting said beam between said pair of buckstays, said means including a pair of vertically aligned brackets each connected to one of said buckstays, means for connecting the opposed end portions of said beam to the aligned brackets of the spaced buckstays, one end of said beam being connected to its respective bracket so as to provide relative movement therebetween to accommodate for thermal contraction and expansion, and means for supporting said tube group on said beam.

13. The invention as claimed in claim 9, in which the tubes extend in directions transverse to the tension members and are supported on beams connected to, and extending transversely of, the buckstays.

14. The invention as claimed in claim 13, in which said wall includes an inner facing of refractory material, the beams are of T-shaped cross-section, the stems of the beams lie between laterally separated portions of the refractory material and are connected to brackets mounted on the buckstays, and the tubes are connected to the portions of the beams lying transversely of the stems.

15. The invention as claimed in claim 14, in whicn the tubes are contiguous, each tube is provided with hooks engaging projections extending from the portions of the beams lying transversely of the stems, and the hooks of each tube cooperate with only every alternate beam.

16. The invention as claimed in claim 13 wherein a pair of said upright walls are angularly disposed with each other with the tubes at the inner side of one of the two walls being united by bends to the tubes at the inner side of the other of the two walls and the distance between the adjacent edges of the walls and the nearest beams of the two walls on which the tubes are supported being such that the bends are able to flex to accommodate thermal expansion of the tubes connected by the bends.

17. In a fluid heating unit having a chamber defined by upright Walls, one of said upright walls comprising a plurality of vertically spaced buekstays extending transversely of said wall, tension members depcndingly sup porting each of said buckstays from the next superjacent buckstay, a plurality of brackets connected at spaced intervals along each of said buckstays, shelf means supported on the brackets of each buckstay, a vertically disposed wall section bottom supported on each of said shelf means, a group of fluid heating tubes screening each of said wall sections, and means for top supporting the screening tube groups of each section from the buclrstay superjacent the wall section screened by the respective tube group.

18. An upright wall as claimed in claim 17, wherein the several vertically spaced buckstays are all suspended from the same tension members.

19. An upright Wall as claimed in claim 18, in which said tension members each include as many rods as the number of vertically spaced buckstays suspended by the tension members, each rod except the lowermost is connected at its lower end to the upper end of a rod immediately beneath it, and each buckstay is suspended from one of the rods of all the tension members.

20. An upright wall as claimed in claim 19, in which each two rods that are connected together are threaded at their adjacent ends and the adjacent ends are screwed into the opposite ends of an internally threaded sleeve.

21. An upright wall as claimed in claim 20, in which the threads on said adjacent ends are of opposite hand and the sleeve acts as a turn-buckle.

22. An upright wall as claimed in claim 19, in which the rods from which any buckstay is suspended pass through the buckstay and the means by which the buckstay is suspended from the rods includes, for each rod, a washer through which the rod passes and on which the buckstay rests, and a nut screwed on to the lower end of the rod to support the washer from below.

23. An upright wall as claimed in claim 19, in which one of: the rods of any tension member has a diameter smaller than that of any rod of the same tension member above said one rod.

References Cited in the file of this patent UNITED STATES PATENTS 1,657,453 Boyd Jan. 31, 1928 1,705,965 De Wolf Mar. 19, 1929 2,144,598 Brinckerhofii et al. Jan. 17, 1939 2,228,938 Wood Ian. 14, 1941 2,333,777 Godshalk Nov. 9, 1943 2,355,800 Hensel Aug. 15, 1944 2,655,238 Langvand Oct. 13, 1953 2,697,420 Lloyd Dec. 21, 1954 2,703,559 Godshalk Mar. 8, 1955 FOREIGN PATENTS 244,565 Great Britain Dec. 24, 1925 

1. IN A FURNACE CHAMBER DEFINED BY UPRIGHT WALLS, ONE OF SAID WALLS COMPRISING A PLURALITY OF SEPARATED, VERTICALLY STACKED WALL SECTIONS EACH INCLUDING BUCKSTAY MEANS FOR BOTTOM SUPPORTING EACH OF SAID VERTICALLY STACKED WALL SECTIONS TO CARRY THE LOAD THEREOF, MEANS FOR TOP SUPPORTING EACH OF SAID BUCKSTAY MEANS AND LOAD CARRIED THEREBY FROM A SUPERJACENT WALL SECTION, AND A GROUP OF HORIZONTALLY DISPOSED TUBES SCREENING EACH OF SAID WALL SECTIONS, EACH GROUP OF TUBES BEING SUPPORTED FROM THE WALL SECTION STACKED ABOVE THE WALL SECTION SCREENED THEREBY. 